How to Choose Extended Interfaces of Rugged In-vehicle Tablet According to Different Needs

Know More about the Features of some Common Extended Interfaces

It’s a common sight that rugged vehicle-mounted tablets with extended interfaces are employed in many industries to enhance working efficiency and realize some specific functions. How to make ensure that the tablets have compatible interfaces with the connected devices and practically meets the specific application requirements has become a concern of buyers. This article will introduce several common extended interfaces of vehicle-mounted rugged tablet to help you better understand the the features of them and choose the most ideal solution.

· CANBus

CANBus interface is a communication interface based on controller area network technology, which is used to connect various electronic control unit (ECU) in automobiles and realize the data exchange and communication among them.

Through the CANBus interface, the vehicle-mounted tablet can be connected to the vehicle’s CAN network to obtain the vehicle status information(such as vehicle speed, engine speed, throttle position, etc.) and provide them for drivers in real time. The vehicle-mounted tablet can also send control instructions to the vehicle system through the CANBus interface to realize intelligent control functions, such as automatic parking and remote control. It is worth noting that before connecting the CANBus interfaces, it is necessary to ensure the compatibility between the interface and the vehicle CAN network to avoid communication failure or data loss.

· J1939

J1939 interface is a high-level protocol based on Controller Area Network, which is widely used in serial data communication between electronic control unit (ECU) in heavy vehicles. This protocol provides a standardized interface for network communication of heavy vehicles, which is helpful for interoperability between ECU of different manufacturers. By using multiplexing technology, the standardized high-speed network connection based on CAN bus is provided for each sensor, actuator and controller of the vehicle, and high-speed data sharing is available. Support user-defined parameters and messages, which is convenient for development and customization according to different specific needs.

· OBD-II

OBD-II (On-Board Diagnostics II) interface is the standard interface of the second-generation on-board diagnostic system, which allows external devices (such as diagnostic instruments) to communicate with the vehicle computer system in a standardized way, so as to monitor and feed back the running status and fault information of the vehicle, and provide important reference information for vehicle owners and maintenance personnel. In addition, the OBD-II interface can also be applied to evaluate the performance status of vehicles, including fuel economy, emissions, etc., to help the owners maintain their vehicles.

Before using the OBD-II scanning tool to diagnose the condition of the vehicle, it must be ensured that the engine of the vehicle is not started. Then insert the plug of the scanning tool into the OBD-II interface located at the lower part of the vehicle cab, and start the tool for diagnostic operation.

· Analog Input

Analog input interface refers to an interface that can receive continuously changing physical quantities and convert them into signals that can be processed. These physical quantities, including temperature, pressure and flow rate, are usually sensed by corresponding sensors, converted into electrical signals by converters, and sent to the analog input port of the controller. Through appropriate sampling and quantization techniques, analog input interface can accurately capture and convert small signal changes, thus achieving high precision.

In the application of vehicle-mounted tablet, analog input interface can be used to receive analog signals from vehicle sensors (such as temperature sensor, pressure sensor, etc.), so as to realize real-time monitoring and fault diagnosis of vehicle status.

· RJ45

RJ45 interface is a network communication connection interface, which is used to connect computers, switches, routers, modems and other devices to a local area network (LAN) or wide area network (WAN). It has eight pins, among which 1 and 2 are used for sending differential signals, and 3 and 6 are used for receiving differential signals respectively, to improve the anti-interference ability of signal transmission. Pins 4, 5, 7 and 8 are mainly used for grounding and shielding, ensuring the stability of signal transmission.

Through the RJ45 interface, the vehicle-mounted tablet can transmit data with other network devices (such as routers, switches, etc.) at high speed and stably, meeting the requirements of network communication and multimedia entertainment.

· RS485

RS485 interface is a half-duplex serial communication interface, which is used for industrial automation and data communication. It adopts differential signal transmission mode, sending and receiving data through a pair of signal lines (A and B). It has strong anti-interference ability and can effectively resist electromagnetic interference, noise interference and interference signals in the environment. The transmission distance of RS485 can reach to 1200m without repeater, which makes it outstanding in applications requiring long-distance data transmission. The maximum number of devices that a RS485 bus can be connected is 32. Support multiple devices to communicate on the same bus, which is convenient for centralized management and control. RS485 supports high-speed data transmission, and the rate usually can up to 10Mbps.

· RS422

RS422 interface is a full-duplex serial communication interface, which allows sending and receiving data at the same time. Differential signal transmission mode is adopted, two signal lines (Y, Z) are used for transmission and two signal lines (A, B) are used for reception, which can effectively resist electromagnetic interference and ground loop interference and greatly improving the stability and reliability of data transmission. The transmission distance of RS422 interface is long, which can reach 1200 meters, and it can connect up to 10 devices. And High-speed data transmission with a transmission rate of 10 Mbps can be realized.

· RS232

RS232 interface is a standard interface for serial communication between devices, mainly used to connect data terminal equipment (DTE) and data communication equipment (DCE) to realize communication, and is known for its simplicity and wide compatibility. However, the maximun transmission distance is about 15 meters, and the transmission rate is relatively low. The maximum transmission rate is usually 20Kbps.

Generally, RS485, RS422 and RS232 are all serial communication interface standards, but their characteristics and application scenarios are different. In short, the RS232 interface is suitable for applications that do not need long-distance fast data transmission, and it has good compatibility with some old equipment and systems. When it is necessary to transmit data in both directions at the same time and the number of connected devices is less than 10, RS422 may be a better choice. If more than 10 devices need to be connected or a faster transmission rate is needed, RS485 may be more ideal.

· GPIO

GPIO is a set of pins, which can be configured in input mode or output mode. When the GPIO pin is in the input mode, it can receive signals from sensors (such as temperature, humidity, illumination, etc.), and convert these signals into digital signals for tablet processing. When the GPIO pin is in the output mode, it can send control signals to actuators (such as motors and LED lights) to achieve precise controls. GPIO interface can also be used as the physical layer interface of other communication protocols (such as I2C, SPI, etc.), and complex communication functions can be realized through extended circuits.

3Rtablet, as a supplier with 18 years’ experience in manufacturing and customizing vehicle-mounted tablets, has been recognized by global partners for its comprehensive customized services and technical support. Whether it is used in agriculture, mining, fleet management or forklift, our products show excellent performance, flexibility and durability. These extension interfaces mentioned above (CANBus, RS232,etc.) are customizable in our products. If you are planing to optimize your workflow and improve the output by the power of tablet, don’t hesitate to contact us to learn more about the product and solution!